They recommend extending the application of the second dose of the Covishield vaccine

In a few days, Cordobans vaccinated against Covid-19 with the Covishield formula should receive the second dose, according to the four weeks provided between each injection.

However, scientific evidence and experts believe that this vaccine is more effective if 12 weeks elapse between the first and second dose.

Covishield is the Indian version of the vaccine produced by AstraZeneca and developed by the University of Oxford. Cordoba has received 44,000 doses out of the 580,000 that the national government has acquired.

Córdoba started applying the first doses of Covishield at the end of February, with which the second dose is expected to be given next week if the four-week schedule is met.

But the scientific literature shows that it is better to allow more time between each injection. The National Department of Health’s Covishield vaccinator manual sets a range of 4 to 12 weeks as the booster interval.

However, he then specifies that although the recommendation of the producer laboratory is to preserve this interval, “the World Health Organization (WHO) in light of the observation that the efficacy and immunogenicity of two doses increase with an interval between doses longer, recommends implementing an interval of 8 to 12 weeks between doses ”.

Scientific proof

Alberto Rosa, researcher at Conicet and consultant in medical genetics at Sanatorio Allende, waits for their mother to postpone the passage for the second dose with Covishield. It is dated March 27.

“There is accumulated evidence that the second dose of the AstraZeneca vaccine should be given at 12 weeks and not at four as they cite in Cordoba. In fact, Buenos Aires already decided a few days ago to give the second dose at 12 weeks ”, explains the researcher.

Rosa then offers a varied bibliography, from British Journal of Medicine Yes The Lancet, which supports this strategy. “The evolution of the efficacy of the AstraZeneca vaccine reaches 82.4% if the second dose is administered at 12 weeks while the efficacy only reaches 54.9% if the second dose is administered before six weeks”, warns -he.

And he adds: “The available doses could be better utilized by waiting 12 weeks and being sure you have a second dose for everyone who has been vaccinated with Covishield.”

Change of strategy

At the end of February, the autonomous city of Buenos Aires set an interval of 10 to 12 weeks for this vaccine, arguing that it increases its effectiveness.

In the UK, a 12-week schedule was decided, a strategy that was also endorsed by the University of Oxford, which developed the formula.

The publications indicate that a single dose of the vaccine already provides 76 percent protection against symptomatic Covid-19 in the first 12 weeks after vaccination.

These studies also found that the vaccine’s efficacy reached 82.4 percent after a second dose in those whose dose interval was 12 weeks or more. If the two doses were given less than six weeks apart, the efficacy was only 54.9%.

Andrew Pollard, principal investigator of the Oxford vaccine trial, said: “The new data supports the policy recommendation made by the UK Joint Committee on Vaccination and Immunization, for a 12 week booster interval, so that they seek the optimal approach. assures us that people are protected 22 days after a single dose of vaccine. “